Attempt to develop an immunofluorescent technique to detect IgE like antibodies on mast cells in the skin of dogs infected with D. canis. Since Schwartzman, Halliwell and Rockey (Antigenic relationship between Human IgE and Canine Ige Clin. Exp. Immunol. 10:399-407, 1972) indicated that IgE like antibodies of dogs and IgE of man contain some biochemically and antigenically similar antigenic determinants, fluorescent labelled and unlabelled anti-human IgE is goind to be used in direct and indirect methods to determine the location of IgE like antibodies in the skin of dogs. Since the use of ALS was successful in suppressing the immunological capacity and producing demodectic mange lesions in dogs, the use of lesser amounts of ALS will be investigated. An attempt will be made to determine the optimum doses necessary for production of lesions in newborn as well as in older animals. The use of mite antigen in combination of Freunds adjuvant to sensitize guinea pigs will be attempted. The antigen will be made from individually collected mites. Preliminary experiments indicate that a crude extract of mites in either physiological saline or in Feunds incomplete antigen is capable of producing delayed hypersensitivity in guinea pigs.